Preheat your oven to 350F/180C.
Cut a pocket into the side of each chicken breast. Stuff each pocket with 1/4 of the mozzarella cheese,1/4 of the sun-dried tomatoes, and some chopped basil. Press the edges of the chicken together or use a toothpick to seal the pocket. Season the chicken with salt and ground black pepper
Place the flour, eggs, and bread crumbs into 3 separate shallow bowls or dishes. Carefully coat the stuffed chicken in flour and shake off the excess. Dip the floured chicken into the beaten eggs, to coat, and then into the breadcrumbs. Make sure to evenly coat the chicken breasts with breadcrumbs.
Heat the vegetable oil in a large pan over medium heat until oil is 350F/180C. Fry the chicken until golden brown on both sides and drain on a paper towel lined plate. Place 2/3 of the marinara sauce evenly on the bottom of a baking dish or other oven safe pan. Place the chicken in the pan of marinara sauce and top with the remaining sauce and the Parmesan cheese.
Bake for 15-25 minutes or until chicken is cooked through and the cheese inside has melted. Allow to cool for a few minutes before garnishing with chopped basil and serving.